The disclosed subject matter relates to polymeric fibers produced by melt-blowing. In particular, the disclosed subject matter relates to composite polymeric fibers produced by melt-blowing a blend of a first polymer and an immiscible second polymer. The composite fiber has an island-in-sea morphology and comprises nanofibers surrounded by a matrix that is selectively soluble by a suitable solvent.
Melt-blowing refers to a polymer laid process whereby streams of molten polymer are subject to hot, high-velocity air to produce a web consisting of fine fibers. Generally, melt-blowing requires five components: an extruder, a metering pump, a die assembly, an air manifold, and a collector. In melt-blowing, a polymer resin is fed into the extruder where it is heated and melted until an appropriate temperature and viscosity are achieved. The molten polymer then is fed to the metering pump which regulates feed rate of the molten polymer to the die assembly. Fine fibers are formed as the molten polymer exits the die assembly and is hit with a stream of hot, high velocity air from the air manifold. The fine fibers then are collected on a collecting device such as a moving screen or a drum.
Here, a polymer blend is utilized in a melt-blowing process to prepare a composite polymeric fiber which has an island-in-sea morphology and comprises nanofibers surrounded by a matrix that is selectively soluble by a suitable solvent. The composite polymeric fiber may be treated with the suitable solvent in order to selectively dissolve the matrix and to obtain the nanofibers.